1. Field of the Invention
The present invention relates to an improvement of a device for deciding abnormality of a longitudinal acceleration sensor which is employed for e.g. a brake fluid pressure control device for a vehicle.
2. Description of the Related Art
Conventionally, a longitudinal acceleration sensor was used to detect the longitudinal acceleration of a vehicle for e.g. a brake fluid pressure control device for a vehicle (for example, see JP-A-9-142281).
If such a longitudinal acceleration sensor falls in an abnormal condition, the control of brake fluid pressure may not be performed suitably. Therefore, the abnormality of the longitudinal acceleration sensor must be decided. In this case, as for a vehicle provided with a driven wheel, the estimated body speed which is computed based on a driven wheel speed can be adopted as a standard for deciding the abnormality. However, as for a four-wheel drive vehicle, the driven wheel speed cannot be acquired. In addition, on uphill running, the inclination of the vehicle in the lengthwise direction affects the detected value of the longitudinal acceleration sensor. In such a case, it is necessary to avoid deciding the abnormality of the longitudinal acceleration sensor.